BEIJING, May 6 (Aljazeera) - China sent 18 warplanes, including fighters and bombers, into Taiwan’s air defence zone, prompting the island’s air force to scramble jets in response to the second-largest incursion so far this year.

Taipei’s defence ministry said the Chinese aircraft crossed into the island’s air defence zone on Friday, forcing the scrambling of Taiwanese aircraft and the deployment of air defence missile systems to track the Chinese planes.

Taiwan, which is claimed by China as its own territory, has complained of repeated such missions by Chinese aircraft, which have become a common occurrence over the past two years or so.

There was no immediate comment from China’s Defence Ministry.

China has described previous incursions as missions to defend the country’s sovereignty and to counter Taiwan’s “collusion” with foreign forces – a veiled reference to US support for Taipei.

The government in Taipei is currently in a heightened state of alert due to fears that China could use Russia’s invasion of Ukraine to make a similar military move on the island, though authorities have not reported any signs Beijing is about to attack.

Friday’s incursion was the second-largest this year after 39 warplanes entered Taiwan’s air defence identification zone (ADIZ) on January 23, according to figures compiled by the AFP news agency. The identification zone is separate from Taiwanese airspace, as the air defence zone covers a broader area that Taiwan patrols as a means to give the island more time to respond to any threats by China.

Parts of Taiwan’s ADIZ also overlap with China’s ADIZ.